MIMO-OFDM (Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing) is a signal transmission method that combines MIMO (Multiple Input Multiple Output) and OFDM (Orthogonal Frequency Division Multiplexing). In a MIMO-OFDM system, subcarriers are orthogonal, and multiple transmit antennas and multiple receive antennas are used to implement transmission and reception, that is, there are at least one transmit antenna and at least one receive antenna. Because MIMO-OFDM can increase a channel capacity, improve spectrum utilization, and also improve reliability of signal transmission, MIMO-OFDM currently has become a mainstream communications technology.
In the MIMO-OFDM system, phase noise is mainly produced by a crystal oscillator. The crystal oscillator is also referred to as crystal oscillator. According to different frequencies of crystal oscillators, degrees of signal distortion caused by generated phase noise are also different. For example, output of an ideal oscillator whose frequency is f0 is α(t)=cos(2πf0t), and output of an oscillator affected by phase noise is α(t)=cos(2πf0t+ϕ(t)), where the phase ϕ(t) is generated randomly, noise caused by the phase ϕ(t) is the phase noise, and compensation for the phase noise is compensation for the phase ϕ(t). In an existing phase compensation method, it is considered by default that receive antennas share a common crystal oscillator (share a common oscillator) and transmit antennas share a common crystal oscillator, that is, all transmit antennas share a common oscillator and all receive antennas also share a common oscillator. However, in an actual MIMO-OFDM system, a case in which receive antennas or transmit antennas do not share a common oscillator may exist. When the existing phase noise compensation solution is applied to the MIMO-OFDM system in which receive antennas or transmit antennas do not share a common oscillator, precision of phase noise compensation for a received signal is relatively low, which may easily cause a case of signal distortion.